In the 3rd Generation Partnership Project (3GPP) that is a mobile communication system standardization project, introduction of a device-to-device communication (D2D) into Release 12 as a new function is under review (see Non Patent Literature 1).
In the D2D communication, direct inter-terminal communication is performed within a terminal group including a plurality of nearby user terminals without intervention of a network. On the other hand, in cellular communication that is common communication of a mobile communication system, user terminals perform communication via a network.
In the D2D communication, radio communication can be performed between nearby user terminals at low transmission power, and thus power consumption of the user terminal and a load of the network can be reduced to be smaller than in the cellular communication.